The window of pleasant weather in Mongolia is very narrow, with June through August being the best time to visit and to view wildlife. During the summer, Mongolia weather is generally mild with temperatures averaging between 60-68 degrees F during the day and dropping to 40-50 degrees F during the night. In the Gobi temperatures can rise to 90 degrees F during the day. Prepare as if you are going to the Rocky Mountains in September: it might be hot, it might rain, and it might snow. Nights in the north could very well go below freezing. Mongolia is generally quite windy, with very little humidity.